, we are told ended up on the desk both of president obama in the white house and of nelson mandela in his office back in south africa. we all know that this past summer when nelson mandela fell ill for the last time, president obama had a trip scheduled to that part of the world. he they did not meet but he did go inside his cell in robben island. here's what he wrote. on behalf of our family, we're deeply humbled to stand where men of such courage faced down injustice and refused to yield. mandela represented and i think michael sheir among others pointed out in the "new york times" today the kind of hope that would become the theme of the president's first campaign. what has been his influence on barack obama and his leadership? >> well, actually, that photo you just took of obama in june of 2013, that was the second time he was in that cell. i was with him the first time in august of 2006 when he was on as a united states senator from illinois when he was on a swing through africa. and he didn't do the kind of high profile signing that you have there, but it was important to him. i